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DATAMATH CALCULATOR MUSEUM

Radio Shack EC-1000

Date of introduction:	1973	Display technology:	Panaplex II
New price:	$89.50	Display size:	8
Size:	9.0" x 6.6" x 2.6"
Weight:	1 pound 12 ounces	Serial No:	D0008494
Batteries:		Date of manufacture:
AC-Adapter:	120 V	Origin of manufacture:	USA
Precision:	8	Integrated circuits:	TMS0109
Memories:
Program steps:		Courtesy of:	Joerg Woerner

Once again we had our doubts about the origin of a Radio Shack calculator. This EC-1000 uses a keyboard similar to the SR-20, sliding knobs like the TI-410 but looks totally different to the sibling TI-3000.

Dismantling a calculator reveals usually within seconds the manufacturer of it, just search a logo on the printed circuit board (PCB), check the main components or think about the mechanical construction. Sometimes we use hints in the manual like the addresses of the Service Facility.

But this EC-1000 was a great exercise !

The internal construction of the EC-1000 looks different to the desktop calculators known from Texas Instruments, but the components are well known:

• The keyboard was manufactured by Texas Instruments
• The display is a Panaplex II type used in the TI-3000
• The calculator circuit is a TMS0109

But finally we found a small number etched on the backside of the PCB and we recognized it: 13-04-709-718. Some other calculators carry numbers with the leading 13-04-709 code and we found the missing link to Texas Instruments with the Montgomery Ward P8F.

PCB Code	Brand	Calculator	Board

13-04-709-478	Montgomery Ward	P8M	Main board
13-04-709-479	Radio Shack	EC-300	Main board
13-04-709-504	Montgomery Ward	P8F	Main board
13-04-709-544	Montgomery Ward	D12K	Main board
13-04-709-698	Montgomery Ward	P8F	Display board
13-04-709-718	Radio Shack	EC-1000	Main board

The rare Montgomery Ward D8F, D10P, and D12K make use of an almost identical housing and very similiar printed circuit boards (PCBs).

The portable calculator EC-300 matches the design of this EC-1000. The successor of the EC-1000 was introduced in 1974 and based on the TI-3500. Don't miss the rare EC-2000.

If you have additions to the above article please email: joerg@datamath.org.